NASSAU COUNTY, Fla. - A 21-year-old Jacksonville man was arrested early Tuesday morning after a monthslong investigation into obscene photos being sent to a child living in Bryceville, according to the Nassau County Sheriff's Office.

The investigation dates back to Dec. 14, 2018, when the Sheriff's Office received a complaint about a child receiving several obscene photos from a man. According to the arrest report, a woman told deputies that her daughter, whose age was redacted, was receiving obscene photos from a young man.

The mother told deputies that she was alerted nine days earlier by a person, whose name was redacted, who told her she needed to check her daughter’s electronic devices, the report shows.

According to detectives, when the girl’s mother began looking through her daughter’s Facebook Messenger account, she found sexually explicit conversations between Trey Roberts and her daughter. The report stated that many of the conversations were "very sexual in nature" and referred to trading photos of each other. According to the report, three nude pictures that were sent Nov. 25, 2018, to her daughter from Roberts’ cellphone were discovered.

The girl's mother told deputies that she was sure that Roberts was aware that her daughter was a minor because her daughter knew his younger brother. The report stated the mother also said that her daughter may have sent him pictures of herself, but could not locate them.

Investigators noted in the report that the girl had access to her social media accounts on both a cellphone and a school-issued laptop. Both devices, along with passwords to the devices and the social media accounts, were collected as evidence.

As the case continued to be investigated, detectives found enough evidence to get a judge to sign off on a warrant for Roberts’ arrest. The warrant was signed Aug. 7 and Roberts was taken into custody and booked just before 2 a.m. Wednesday into the Nassau County jail on a charge of transmission of materials harmful to minors by electronic means.

He was released about 90 minutes later from jail on $10,000 bond, online jail records show. Prior to Tuesday’s arrest, Roberts had no criminal history.

News4Jax crime and safety expert Ken Jefferson stressed that parents need to keep a watchful eye on their children’s social media activities to see who they are communicating with.

“There's a lot of predators out there lurking. They are looking for child victims. They're looking for vulnerable people who will engage them in some type of conversation," Jefferson said. “Sometimes there are innocent children who don’t know any better. Then again, there are some children that are very young and know exactly what they’re doing.”

On Wednesday, News4Jax went to the home listed on the arrest report for Roberts to see if he would talk, but a man claiming to be his relative came out and told the crew to get out of the yard.